Method for monitoring a rotational angle sensor on an electrical machine

• US 6,426,633 B1
• Filed: 06/14/2000
• Issued: 07/30/2002
• Est. Priority Date: 06/18/1999
• Status: Expired due to Fees

• Current Assignee: Danfoss Drives A/S (Danfoss A/S)
• Original Assignee: Danfoss Drives A/S (Danfoss A/S)
• Inventors: Thybo, Claus
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): SUNDARAM, T R
• Application Number:
  US09/593,408
• Time in Patent Office: 776 Days
• Field of Search: 324/537, 324/545, 324/163, 324/167, 324/162, 324/160, 324/158.1, 324/511, 324/510
• US Class Current: 324/511
• CPC Class Codes: G01R 31/2829 Testing of circuits in sensor or actuator systems testing of apparatus for measuring electric or magnetic variables G01R35/00; testing of indicating or recording apparatus G01D; in airbag systems B60R21/0173; checking gas analysers G01N33/007; monitoring or fail-safe circuits for electromagnets H01F7/1844
• CPC Class Codes: H02P 21/14 Estimation or adaptation of machine parameters, e.g. flux, current or voltage
• CPC Class Codes: H02P 2203/05 Determination of the rotor position by using two different methods and/or motor models
• CPC Class Codes: H02P 6/16 Circuit arrangements for detecting position
• CPC Class Codes: H02P 6/181 using different methods depending on the speed
• CPC Class Codes: H02P 9/02 Details of the control

Abstract

A method for monitoring a rotational angle sensor on an electrical machine. It is desired to provide a method that enables fault detection at both high speeds and low speeds of the rotor. The electrical power of the machine is measured and a power value is estimated using the output signal of the rotational angle sensor, a residual being formed from the measured power and the estimated power and the time curve of the residual being monitored.

Claims

1. Method for monitoring a rotational angle sensor on an electrical machine, comprising the steps of measuring the electrical power of the machine, estimating a power value using an output signal of the rotational angle sensor, forming a power residual from the measured electrical power and the estimated power value, and monitoring a time curve of the power residual.

2. Method according to claim 1, in which an error threshold is specified and an error is assumed in the output signal when the power residual exceeds the error threshold.

3. Method according to claim 2, including the further step of discarding the estimated power valve within a predetermined period after the error threshold has been exceeded.

4. Method according to claim 1, in which a fault is assumed when an increase in the power residual over time exceeds a predetermined limit value.

5. Method according to claim 1, in which when a fault occurs, the output signal of the rotational angle sensor is not used to control the electrical machine.

6. Method according to claim 1, in which the estimated power value is formed by a load part, a rotor loss part, a stator loss part and a magnetizing part.

7. Method according to claim 6, in which the output signal of the rotational angle sensor enters only into the load part.

8. Method according to claim 1, including, in the event of a fault, the further step of shutting the machine down gently after a fault occurs.